[Crash-utility] [PATCH] Fix trace extension for v3.15+

[Dave Anderson]

----- Original Message -----
> Hello Rabin,
> 
> This patch looks good to me.
> 
> Reviewed-by: Qiao Nuohan <qiaonuohan at cn.fujitsu.com>

Rabin, thanks for the patch, and Qiao, thanks for the quick review.

Queued for crash-7.1.0:

  https://github.com/crash-utility/crash/commit/28a2bd99a9e514469ef61864e68212ebace613a6

Dave


  
> 
> On 02/05/2015 05:40 AM, Rabin Vincent wrote:
> > Since Linux v3.15 (specifically, the following commit), the event name is
> > optionally moved to another structure.
> >
> > commit de7b2973903c6cc50b31ee5682a69b2219b9919d
> > Author: Mathieu Desnoyers<mathieu.desnoyers at efficios.com>
> > Date:   Tue Apr 8 17:26:21 2014 -0400
> >
> >      tracepoint: Use struct pointer instead of name hash for reg/unreg
> >      tracepoints
> >
> > -       char                    *name;
> > +       union {
> > +               char                    *name;
> > +               /* Set TRACE_EVENT_FL_TRACEPOINT flag when using "tp" */
> > +               struct tracepoint       *tp;
> > +       };
> >
> > This patch handles this in the trace extension so that both kernels with and
> > without that commit work.
> > ---
> >   extensions/trace.c | 46 ++++++++++++++++++++++++++++++++++++++++++----
> >   1 file changed, 42 insertions(+), 4 deletions(-)
> >
> > diff --git a/extensions/trace.c b/extensions/trace.c
> > index a09f6a1..8639fb2 100644
> > --- a/extensions/trace.c
> > +++ b/extensions/trace.c
> > @@ -988,19 +988,42 @@ static void ftrace_destroy_event_types(void)
> >   	free(ftrace_common_fields);
> >   }
> >
> > +#define TRACE_EVENT_FL_TRACEPOINT 0x40
> > +
> >   static
> >   int ftrace_get_event_type_name(ulong call, char *name, int len)
> >   {
> >   	static int inited;
> >   	static int name_offset;
> > +	static int flags_offset;
> > +	static int tp_name_offset;
> > +	uint flags;
> >
> >   	ulong name_addr;
> >
> > -	if (!inited) {
> > -		inited = 1;
> > -		name_offset = MEMBER_OFFSET("ftrace_event_call", "name");
> > -	}
> > +	if (inited)
> > +		goto work;
> > +
> > +	inited = 1;
> > +	name_offset = MEMBER_OFFSET("ftrace_event_call", "name");
> > +	if (name_offset>= 0)
> > +		goto work;
> >
> > +	name_offset = ANON_MEMBER_OFFSET("ftrace_event_call", "name");
> > +	if (name_offset<  0)
> > +		return -1;
> > +
> > +	flags_offset = MEMBER_OFFSET("ftrace_event_call", "flags");
> > +	if (flags_offset<  0)
> > +		return -1;
> > +
> > +	tp_name_offset = MEMBER_OFFSET("tracepoint", "name");
> > +	if (tp_name_offset<  0)
> > +		return -1;
> > +
> > +	inited = 2;
> > +
> > +work:
> >   	if (name_offset<  0)
> >   		return -1;
> >
> > @@ -1008,6 +1031,21 @@ int ftrace_get_event_type_name(ulong call, char
> > *name, int len)
> >   			"read ftrace_event_call name_addr", RETURN_ON_ERROR))
> >   		return -1;
> >
> > +	if (inited == 2) {
> > +		if (!readmem(call + flags_offset, KVADDR,&flags,
> > +			     sizeof(flags), "read ftrace_event_call flags",
> > +			     RETURN_ON_ERROR))
> > +			return -1;
> > +
> > +		if (flags&  TRACE_EVENT_FL_TRACEPOINT) {
> > +			if (!readmem(name_addr + tp_name_offset, KVADDR,
> > +				&name_addr, sizeof(name_addr),
> > +				     "read tracepoint name", RETURN_ON_ERROR))
> > +				return -1;
> > +		}
> > +
> > +	}
> > +
> >   	if (!read_string(name_addr, name, len))
> >   		return -1;
> >
> 
> 
> --
> Regards
> Qiao Nuohan
> 
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